The present invention relates to devices for stripping insulation from electric wires. Electic wires generally have a relatively thick coating of electric insulation material surrounding the wire along its length. When the wire is initially installed, or when new connections of pre-installed wiring are to be made, it is necessary to strip the insulation from the end of the wire a sufficient distance to provide a good electrical connection.
Various problems have existed with prior art wire stripping devices which hindered both the speed and the quality of the stripping operation. For example, in one type of wire stripping device, a portion of the device would grip the insulation, while a pair of cutters moved radially inwardly to cut a portion of the insulation and then moved axially away from the grippers to strip the insulation. In such devices, there was the risk that where the insulation was greasy or otherwise slippery, the gripping means would slide on the insulation, thereby hampering the stripping operation. In other instances, the insulation was of such a tough, such as fibrous, material, that the speed, and sometimes the effectiveness of the stripping operation was severely hampered.
Some of the stripping devices required the device to be at right angles rather than parallel to the wire. This hampered many stripping operations where it was difficult to use the strippers at such right angle position.
A still further problem existed in stripping a bent wire. In stripping a wire by a device that moved axially of the wire, the device often straightened the wire. This presented further difficulties in speed of performance and incurred the risk of a breaking or otherwise deforming the wire.
A further difficulty with prior art devices related to the degree and kind of cutting necessary for proper stripping action to occur. In some such devices, for example, the blades were semi-circular in cross section. The particular shape was used so that the blades could but all or most of the insulation, by providing a completely circular cutting surface when the blades were closed to the desired extent. One problem with such device was that a different cutter would be needed for different sizes of wire; otherwise, the aforesaid circular relationship could not be achieved.
In other types of devices, the blades were V-shaped. Such shapes provided an inadequate stripping action. For example, the device would go off-center if one blade was sharper than the other, resulting in a cutting or nicking of the wire. Moreover, the device would often wobble or move laterally in the stripping action so as to leave portions of the insulation adhered to the wire. Moreover, in devices where the V-shaped cutters were used, such as in U.S. Pat. No. 3,880,022, it was difficult to cut a sufficient amount of insulation so as to be ineffective on many types of insulation.
In some other prior art devices, in order to increase the potential for stripping wire despite the hardness or the toughness of the insulation material, it was necessary to adjust the cutting blade depth to come so close to the conductive wire that there was a tendency to nick, cut or otherwise distort the conductive wire.